Laszlo Ersek 98a4d04e8f MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled) variants of IoWriteFifoXX() ...

In commit b6d11d7c46 ("MdePkg: BaseIoLibIntrinsic (IoLib class)
library", 2017-04-12), the MOV instructions in the write loops were
probably copied from the read loops. However, the operand order was not
adjusted.

As a result, the IoWriteFifoXX() routines, when invoked in SEV guests, now
overwrite the source buffer with value 0x01 / 0x0001 / 0x00000001 -- the
SevNoRepIo() function returns value 1 in EAX, in SEV guests --, and write
the same value to the target IO port.

Fix this by putting the target operand (AL / AX / EAX) first, and the
source operand (BYTE / WORD / DWORD [ESI/RSI]) second.

Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Fixes: b6d11d7c46
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>

2017-09-11 22:28:05 +02:00

7.3 KiB

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